The widespread division between mental health and criminal justice systems leads to many persons with serious mental illnesses being arrested and incarcerated when mental health treatment would be more appropriate. The criminalization of such individuals is an extensively documented problem across the U.S. As illustrated by the Sequential Intercept Model, the most effective point of intervention within the criminal justice system to prevent unnecessary arrest and incarceration is the initial encounter between an officer and a person with a serious mental illness, which is the first step in criminal justice involvement. This R34 project seeks to implement a trial of a new police-mental health linkage system and to test its feasibility and acceptability among end-users. Our new linkage system will consist of three steps. First, some individuals who have a serious mental illness and a history of criminal justice involvement will give special consent to allow a brief disclosure of their mental health status to be included as part of a registry in the state's criminal justice information system. Second, when an officer runs an enrolled participant's name or identifiers as part of a routine background check during an encounter, the officer will receive an electronic message that the person has special mental health considerations, and to call a 1-800 number for more information that will connect to our Linkage Specialist. Lastly, the Linkage Specialist, who will b a certified mental health provider, will assist the officer by thinking through observed behaviors and potential resolutions with the officer. We expect that in some cases where an arrest is not obligatory, the officer will then choose to refer to or transport to mental health services instead of making an arrest because of the information provided by our straight-forward, low- cost system. Three overarching aims will guide this pilot intervention project. In Aim A, we will implement a demonstration of the police-mental health linkage system in order to operationalize procedures and develop the protocol manual (for a larger study) through collaboration with three key partners, the Georgia Bureau of Investigation (which maintains Georgia's criminal justice database/information system), the Savannah- Chatham Metropolitan Police Department, and the local community mental health agency, Gateway Behavioral Health Services. In Aim B, we will assess all key stakeholder groups' perceptions of acceptability through focus groups conducted with patients, patrol officers, police department leaders, and mental health services program managers. In Aim C, we will demonstrate feasibility and estimate effect size and other parameters to prepare for a larger-scale study. Feasibility will be examined among 200 participants with a serious mental illness and a criminal justice history. Their number of arrests during the 1-year intervention will be compared to the prior year, and we will assess the how many calls result in arrest versus mental health service linkage. To examine how the linkage system worked and the ways it impacts decision-making, we will also conduct individual interviews with officers who make use of the system, and the Linkage Specialists who take their calls.